Portable writing surface



FIG. 1 is a perspective view of our new design for a portable writing surface.

FIG. 2 is a top plan view, the opposite side being a mirror image thereof.

FIG. 3 is a rear elevation view thereof.

FIG. 4 is a front elevation view thereof; and,

FIG. 5 is a left side elevation view, the opposite side being a mirror image thereof. 

The ornamental design for a portable writing surface, as shown and described. 